1. The signature of the undertaker has expired, that is, the signature of the undertaker has exceeded the time limit. I Dongguan workers' signature expired because any software running on the system mobile phone needs signature verification, and software without signature cannot be used in the system. The operation signature on the system refers to the audit of the developer's account, which usually sets a limited time. After the time expires, when running the program, you will be prompted that the signature has expired. Now you need to obtain the authentication of the developer account before you can continue to use it.